1. Field of the Invention
The present invention relates to a switching device and a portable telephone and, more particularly, to a switching device by which a predetermined item can be selected with reliability and a portable telephone having the same.
2. Description of the Background Art
In a portable telephone, a terminal, or the like, a switching device is used so that the user can select or input a predetermined item. For example, Japanese Patent Laying-Open Nos. 11-163997 and 2000-173404 disclose such a switching device. FIG. 18 shows the basic structure of the switching device disclosed in the publications. The switching device has a wheel 101 rotating about a rotary shaft 103 and a switch 102. Rotary shaft 103 of wheel 101 is provided with a rotary encoder 104. Switch 102 is provided below wheel 101.
In the switching device, by rotating wheel 101 with a finger or the like as shown by an arrow 110, a predetermined item can be selected. By pressing wheel 101 itself downward as shown by an arrow 111, switch 102 can be turned on or off.
Such a switching device has, however, the following problems. As shown in FIG. 18, in order to rotate wheel 101, a certain extent of frictional force is necessary between the finger and wheel 101. When the force of pressing wheel 101 is increased to certainly obtain such a frictional force, there is a case such that wheel 101 is pressed in to operate switch 102.
On the other hand, in the case of pressing wheel 101 to turn on/off switch 102, if the peripheral portion of wheel 101 almost right above rotary shaft 103 is not pressed, there is a case such that wheel 101 rotates and a selected item changes.
The invention has been achieved to solve the problems. An object of the invention is to provide a switching device by which the user can perform a switching operation with reliability. Another object is to provide a portable telephone having such a switching device.
According to a first aspect of the invention, there is provided a switching device having a wheel rotating about a rotary shaft, which includes: a movable mechanism and first and second switches. The movable mechanism allows the wheel to move to one side and the other side approximately along a direction of extension of the rotary shaft. The first and second switches are disposed on the one side and the other side while sandwiching the wheel, each of which performs a switching operation when being come into contact with the wheel by the movable mechanism.
With the configuration, by the movement to the one side or the other side of the wheel almost about the rotary shaft by the movable mechanism, the first or second switch is turned on/off. Unlike the conventional switching device, the switch disposed below the wheel is not turned on/off at the time of rotating the wheel, so that erroneous operation can be suppressed. Since the switching device is not disposed below the wheel, the height of the switching device can be further reduced.
Preferably, the movable mechanism allows the wheel to be tilted about another rotary shaft provided for the wheel. The wheel can be easily tilted.
Preferably, the another rotary shaft is disposed in a position passing the center of the wheel, and the first and second switches are disposed while sandwiching the another rotary shaft, on the side opposite to the portion where the wheel is allowed to perform the tilting operation.
Preferably, the another rotary shaft is disposed in a position apart from the center of the wheel from the portion where the wheel is allowed to perform the tilting operation, and the first and second switches are disposed between the another rotary shaft and the portion where the wheel is allowed to perform the tilting operation. Consequently, the distance from the portion where the wheel is allowed to perform the tilting operation to the another rotary shaft becomes longer, so that the wheel can be tilted more easily.
Alternately, it is preferable that the movable mechanism permits the wheel to slide along the rotary shaft.
Particularly in this case, the movable mechanism includes resilient members attached to the one side and the other side of the rotary shaft of the wheel. The resilient members have energizing force toward the wheel. Consequently, the first and second switches can be prevented from being erroneously turned on/off.
According to another aspect of the invention, there is provided a portable telephone having a switching device including a wheel, a movable mechanism, and first and second switches. The wheel rotates about a rotary shaft. The movable mechanism allows the wheel to move toward one side and the other side approximately along a direction of extension of the rotary shaft. The first and second switches are disposed on the one side and the other side while sandwiching the wheel and perform a switching operation when being comes into contact with the wheel by the movable mechanism.
With the configuration, the first or second witch can be turned on/off by moving the wheel to the one side or the other side almost along the rotary shaft by the movable mechanism. Unlike the conventional portable telephone, the switches disposed below the wheel are not turned on/off at the time of rotating the wheel, so that erroneous operation can be prevented. Since the switching device is not disposed below the wheel, a smaller portable telephone can be achieved.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.